The present invention relates, in general, to an overcurrent sensing circuit for use with a voltage regulator, such as a linear post regulator for a power supply.
In conventional voltage regulators, overcurrent protection is usually achieved by inserting a sense resistor into the current path of the regulator. Current flowing through this resistor develops a voltage which is proportional to the current by virtue of Ohm's law. This voltage is measured and compared to a reference voltage, and when the reference voltage level is exceeded, the current to the regulator is cut off, or otherwise inhibited, such that no damage occurs thereto.
A drawback to this type of overcurrent sensor, is that the current sense resistor introduces a power loss in the regulator circuit that reduces the circuit's efficiency. In addition, the sense resistor adds an additional element to the circuit, and increases the physical size of the regulator. This is of further significance in systems which employ a plurality of voltage regulators, such as a multiple output power supply.